A person's taste in music Changes with time, across moods, across experiences and age.i have rarely met a person who has stayed loyal to Only the one kind or style of music
for example , When we are young, we generally like peppy & 'loud' music . but as we age, one's taste mellows down a bit - some of it is physical & physiological too
Youth also has a lot of Peer-pressure/conformity or Rebellion against the establishment, too to encounter & our Real tastes may remain Latent till much later, when we are more confident & Know & Accept ourselves.
Most individuals seem to grow out of their youthful tastes in their 40s & later. They are good for nostalgia [down memory lane ;-)] but can rarely Recapture that euphoria & emotions.
Then again, our tastes may differ when we are in different moods &/or phases of our life. You don't like a happy song when sad & vice-versa ;-) Or how about when one is in love as against when one is dumped !
Sometimes, if one shifts base, migrates to a new country & culture, their tastes may change again.
So to paraphrase, a person's taste in music may Reflect a particular phase in one's personality/life, but wouldn't Define their personality. Since personality itself is not Static or Given, but can change & modify with time, etc. so also musical tastes can, if at all, only capture a tiny image of a person.
But I also want to add that an individual's taste May become a point of Judgment or Stereotyping or Ribbing, especially in the clique subcultures. To that extent, even if the preference may be temporal, it has greater consequential effects